1. Field of the Invention
The present invention relates to locking devices used in automotive applications. The invention more particularly concerns the locking of a steering shaft to a steering column of an automobile so as to prevent rotation of the steering shaft during selected periods of time. Thus, the locking device can be used as a safety device and an anti-theft device.
2. Discussion of the Background
For years now, automobile manufacturers have been including, as a standard feature, the feature of an immobilized steering shaft when the ignition key is not inserted into the ignition switch. The immobilized steering shaft prevents the steering wheel from rotating, thus, someone not having the ignition key can not steer the car if the car is hot-wired or if someone attempts to push the car away. The theft deterrent function works so well that people who attempt to take a car without using a key, typically, employ a large screwdriver-type of device inserted into the opening for the ignition key to break, bust open, and remove the ignition device that immobilizes the steering shaft. Thus, in a single act of violence, the person breaking into the vehicle can disable both the ignition function and the steering immobilization function. Once, the person has successfully removed the device, the vehicle can then be easily hot-wired and driven away. Such a device that integrates the two functions is disclosed in U.S. Pat. No. 5,848,540. FIG. 6 is a perspective view of a portion of a steering column 180 that accommodates a combined ignition switch and steering wheel anti-rotation device.
Attempts have been made to separate the ignition function and the anti-rotation of the steering wheel function in an attempt to make more complicated the act of automobile theft. The person attempting to steal an automobile will now need to disengage the anti-rotation device and the ignition switch separately, which will consume much more time and make it more likely that the person will be caught in the act. As such, it is presumed that a person inclined to steal the automobile of another person will not do so since the risk is not worth the effort. An example of a device that focuses on one of the functions, the anti-rotation function, is disclosed in U.S. Pat. No. 5,896,765, and European Patent Application No. EP764566A1. However, the highly motivated car thief may take their chances and attempt to steal an automobile incorporating the steering wheel locking devices disclosed in U.S. Pat. No. 5,896,765. The car thief would find that the locking element is one large piece of material. The car thief can beat or impact on it with push loads and either bend it, locally bend the steering shaft, or break the housing around the locking element, thus disarming the locking function.
An added benefit of placing the ignition switch in another location such as the dashboard is that the steering column area is made less busy for the driver of the vehicle. This is important since, currently, the steering column area is very busy, since it incorporates controls for directional indicators, head lamps, cruise control, windshield wipers, and etc.
Thus, there is a need for a steering lock device which is separate from the ignition switch and which prevents the destruction of the locking element when a thief attempts to disengage the steering lock device.